To eliminate the possibility of nail-jamming in a sheet connecting nail-manufacturing machine for manufacturing sheet-connecting nails by mounting the nails on a plastic sheet.

A projecting portion 8Ra is provided at a lower part of the front surface of a right side nail guide rail 8R positioned on the rear side with respect to the normally rotational direction of an index wheel 7, and the projecting portion 8Ra is projected toward a position farther forward than a leg of a nail charged into a helical groove of the index wheel 7. If the index wheel charged with the nail is made to rotate in a reverse direction, the leg of the nail impinges against the projecting portion 8Ra of the guide rail 8R to block the reverse rotation, so that nail jamming to be caused by the reverse rotation of the index wheel can be prevented.